Hidden, scroll, auto in CSS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What happens when overflow: hidden; is applied?

If a container has content larger than its size and overflow: hidden; is set, what will the user see?

A The container expands to fit all content, ignoring its set size.

B Scrollbars appear allowing the user to scroll to see the extra content.

C The extra content is visible outside the container boundaries.

D The extra content is clipped and not visible or scrollable.

💡 Hint

Think about what 'hidden' means in everyday life, like hiding something behind a curtain.

overflow: hidden; clips any content that goes beyond the container's size. The user cannot scroll to see it, so it is effectively hidden.

📝 Syntax

intermediate

Which CSS rule correctly enables scrollbars only when needed?

You want scrollbars to appear only if the content is bigger than the container. Which CSS overflow value should you use?

A overflow: visible;

B overflow: scroll;

C overflow: auto;

D overflow: hidden;

💡 Hint

Think about a door that opens only when someone wants to enter.

overflow: auto; shows scrollbars only if the content is larger than the container. scroll always shows scrollbars, even if not needed.

❓ rendering

advanced

What will the user see with this CSS?

Given this HTML and CSS, what will the user see in the browser?

<div class="box">This is a very long text that will not fit inside the box.</div>

.box { width: 10rem; height: 3rem; overflow: scroll; border: 1px solid black; }

A A box that clips the text and shows no scrollbars.

B A 10rem by 3rem box with scrollbars allowing the user to scroll to see all the text.

C A box that expands to fit all the text without scrollbars.

D A box with no border and no scrollbars.

💡 Hint

Scroll means you can move the content inside the box to see hidden parts.

overflow: scroll; always shows scrollbars, so the user can scroll inside the fixed-size box to see all content.

❓ selector

advanced

Which CSS selector targets only elements with overflow set to auto?

You want to style only elements that have overflow: auto; set in their inline style attribute. Which selector works?

A [style*="overflow: auto"]

B .auto-overflow

C [overflow="auto"]

D :overflow(auto)

💡 Hint

Attribute selectors look inside the HTML tag's attributes.

[style*="overflow: auto"] selects elements whose style attribute contains the text overflow: auto. Other options are invalid or select by class or non-existent pseudo-class.

❓ accessibility

expert

How to ensure keyboard users can scroll a container with overflow: auto;?

You have a scrollable container with overflow: auto;. What is the best way to make sure keyboard users can scroll it?

A Add <code>tabindex="0"</code> to the container so it can receive keyboard focus.

B Remove all focusable elements inside the container.

C Set <code>overflow: hidden;</code> to prevent scrolling.

D Add <code>aria-hidden="true"</code> to hide it from screen readers.

💡 Hint

Keyboard users need to focus on the container to scroll it with arrow keys.

Adding tabindex="0" makes the container focusable by keyboard. Then users can scroll it using keyboard arrows. Hiding it or removing focusable elements prevents accessibility.

Practice

1. What does the CSS property overflow: hidden; do to extra content that doesn't fit in a container?

easy

A. It always shows scrollbars to access extra content.

B. It enlarges the container to fit all content.

C. It shows scrollbars only if the content overflows.

D. It hides the extra content without showing scrollbars.

Solution

1. Step 1: Understand overflow: hidden; behavior

   This property hides any content that goes beyond the container's size without showing scrollbars.

2. Step 2: Compare with other overflow values

   Unlike scroll or auto, it does not provide any way to scroll to hidden content.

3. Final Answer:

   It hides the extra content without showing scrollbars. -> Option D

4. Quick Check:

   hidden hides overflow [OK]

Hint: Hidden means no scrollbars, just cut off content [OK]

Common Mistakes:

• Thinking hidden shows scrollbars
• Confusing hidden with auto
• Assuming content resizes container

2. Which of the following is the correct CSS syntax to always show scrollbars on overflow?

easy

A. overflow: auto;

B. overflow: scroll;

C. overflow: hidden;

D. overflow: visible;

Solution

1. Step 1: Recall CSS overflow values

   scroll always shows scrollbars regardless of content size.

2. Step 2: Verify syntax correctness

   The syntax overflow: scroll; is valid and forces scrollbars.

3. Final Answer:

   overflow: scroll; -> Option B

4. Quick Check:

   scroll always shows scrollbars [OK]

Hint: Scroll means scrollbars always visible [OK]

Common Mistakes:

• Using auto instead of scroll
• Confusing hidden with scroll
• Writing invalid property names

3. Given this CSS and HTML:

div {
  width: 100px;
  height: 100px;
  overflow: auto;
  border: 1px solid black;
}

This is a very long text that will overflow the box and may require scrolling.

What will the user see in the browser?

medium

A. No scrollbars, content is cut off.

B. Scrollbars always visible even if not needed.

C. Scrollbars appear only if content overflows.

D. Content expands container size to fit all text.

Solution

1. Step 1: Understand overflow: auto; behavior

   This value shows scrollbars only when content is bigger than the container.

2. Step 2: Analyze the content size

   The text is longer than 100px width and height, so scrollbars will appear.

3. Final Answer:

   Scrollbars appear only if content overflows. -> Option C

4. Quick Check:

   auto shows scrollbars if needed [OK]

Hint: Auto means scrollbars only if content is too big [OK]

Common Mistakes:

• Thinking auto always shows scrollbars
• Assuming content resizes container
• Confusing auto with hidden

4. You want to hide overflow content but accidentally wrote overflow: auto hidden; in your CSS. What will happen?

medium

A. The first value auto sets horizontal overflow, hidden sets vertical overflow.

B. The browser will ignore the entire overflow property.

C. The browser will show scrollbars always.

D. The CSS will cause a syntax error and not apply.

Solution

1. Step 1: Understand CSS overflow shorthand

   overflow can take one or two values: first for horizontal, second for vertical overflow.

2. Step 2: Analyze two-value syntax

   auto hidden is valid shorthand: horizontal = auto, vertical = hidden.

3. Final Answer:

   The first value auto sets horizontal overflow, hidden sets vertical overflow. -> Option A

4. Quick Check:

   Two-value overflow sets horizontal and vertical separately [OK]

Hint: Two values set horizontal and vertical overflow separately [OK]

Common Mistakes:

• Thinking invalid syntax causes error
• Assuming both values apply as one
• Ignoring two-value overflow shorthand

5. You have a container with fixed width and height. You want to ensure that if content overflows horizontally, a scrollbar appears, but vertically overflow content is hidden without scrollbars. Which CSS is correct?

hard

A. overflow-x: scroll; overflow-y: hidden;

B. overflow-x: hidden; overflow-y: scroll;

C. overflow: scroll;

D. overflow: auto;

Solution

1. Step 1: Identify horizontal and vertical overflow needs

   Horizontal overflow needs scrollbars, vertical overflow should hide content.

2. Step 2: Use directional overflow properties

   overflow-x: scroll; forces horizontal scrollbars, overflow-y: hidden; hides vertical overflow.

3. Step 3: Check other options

   overflow: scroll; shows scrollbars both directions; overflow: auto; shows scrollbars only if needed both directions; overflow-x: hidden; overflow-y: scroll; reverses the requirement.

4. Final Answer:

   overflow-x: scroll; overflow-y: hidden; -> Option A

5. Quick Check:

   Directional overflow controls scrollbars separately [OK]

Hint: Use overflow-x and overflow-y for separate scroll control [OK]

Common Mistakes:

• Using single overflow property for different directions
• Confusing scroll and auto
• Forgetting to hide vertical overflow